The present invention relates to methods and apparatus for production of hydrocarbons. More specifically, the present invention relates to methods and apparatus for mounting to the well head of an oil and/or gas well, particularly a tight or low pressure well with limited production, for use in producing hydrocarbons from the well.
It is common practice in the oilfield to pump hydrocarbons from oil and gas wells, but there are many wells that do not produce hydrocarbons at a rate sufficient to justify the capital cost of pumping equipment and/or the energy and maintenance costs of operating the pumping equipment. Even though such wells may be steady producers, they produce at such low volumes that the operator simply cannot afford to produce from the well, effectively requiring that the pump be removed from such wells and that the wells be capped.
The most prevalent form of artificial lift system for relatively shallow and low-volume wells is sucker-rod pumps. Rod pumping uses arm-like devices to provide up-and-down motion to a downhole pump. However, expensive workover rigs and personnel are needed to replace the downhole pumps and pull the sucker rods. The present invention has eliminated the sucker-rod pumps themselves and the need for expensive workover rigs.
One alternative to wellhead pumping equipment, at least for gas fields, is a plunger lift system. A plunger lift system relies on bottom hole pressure. A plunger is inserted downhole and the well is shut-in to allow pressure to build. However, such systems have proven ineffective in many areas due to lack of gas pressure. The present invention does not require bottom hole pressure to operate and does not require a shut-in time to wait for the pressure to build.
U.S. Pat. No. 5,097,901 addresses these problems to some extent by providing a so-called mobile pumping apparatus that is mounted on a truck or tractor chassis and that actually lifts oil from the well with swab cups on a swab bar that is mounted on the end of a cable. After the wellhead equipment is removed from the well, the truck or tractor drives to the wellhead. The swab bar is lowered down into the well and then retrieved, pulling the liquids in the well up with the swab and into a storage tank mounted on the truck or tractor.
Although the mobile pumping apparatus of the type disclosed in U.S. Pat. No. 5,097,901 works well for many wells, particularly wells that are closely spaced in a single field, it does have certain disadvantages and limitations. For instance, they are not useful for producing gas from a well. Also, the wells serviced by such mobile pumping apparatus are open to the atmosphere, allowing the casing to oxidize. Further, although they are effective for producing oil accumulated in a well bore, the most important limitation of mobile pumpers may be that they are not capable of increasing production from a well with low bottom hole pressure above historical yield (and the bottom hole pressure is low in most fields in which mobile pumpers are used). Consequently, their use in a field with low bottom hole pressure does not optimize production from the field.
Another problem with production of hydrocarbons from many fields (not just fields with low bottom hole pressure) is the environmental impact of producing the hydrocarbons. There are many such environmental problems that must be overcome and/or minimized, but describing one such problem will illustrate the advantages of the present invention. Specifically, the production from wells that are being pumped eventually decreases as a result of the accumulation of particulates, paraffin, and/or other materials in the well and/or well bore. To increase production from such wells requires pulling the sucker rods from the well so that the well bore can be swabbed, acidized, perforated, and/or any of several other operations. Of course the sucker rods are immersed in oil, and when they are pulled from the well, the oil must be contained rather than allowed to drip on the ground around the well. Because the present invention does not use sucker rods, this source of environmental contamination is eliminated from the hydrocarbon production process, and it is therefore an object of the present invention to decrease the environmental impact of producing hydrocarbons from wells.
It is also an object of the present invention to address some of these other limitations and disadvantages of prior art methods and apparatus for producing hydrocarbons from wells, particularly in wells that produce relatively small quantities of hydrocarbons and/or produce hydrocarbons irregularly. More particularly, it is an object of the present invention to provide methods and apparatus for producing hydrocarbons from wells that provide the capability of producing gas as well as oil, that maximize production from the well, and that require minimal operator intervention.
It is also an object of the present invention to provide a method and apparatus for producing both gas and oil from a well.
It is also an object of the present invention to provide a method and apparatus for producing hydrocarbons from a well in a field with low bottom hole pressure.
Another object of the present invention is to provide a sealed system for producing hydrocarbons from a well that reduces oxidation of the casing of the well and stimulates production from the well.
It is also an object of the present invention to provide a method and apparatus for controlling the production of hydrocarbons from several wells in a field.
It is also an object of the present invention to provide a method and apparatus for controlling the production of hydrocarbons from one or more wells from a remote location.
Yet another object of the present invention is to provide a method and apparatus that decreases the cost of producing the hydrocarbons from one or more wells.
Conventional swabbing units and the above-described mobile pumping apparatus place considerable strain on the swab cups during the retrieval of the swab from downhole, and it is therefore also an object to increase the life of the swab cups utilized to produce hydrocarbons from a well bore in accordance with the method and apparatus of the present invention.
Other objects and advantages of the present invention will be made clear to those skilled in the art by the following description of the presently preferred embodiments thereof.